Packless stuffing box annular seal assembly

ABSTRACT

An improved annular seal assembly and packless stuffing box for an oil pumping unit of the type having a polished rod reciprocatingly extending therethrough and downhole to a pump located at the lower end of a borehole. The stuffing box has a main body that terminates in a tubing adaptor at the lower end thereof by which it can be mounted to the upper end of the tubing of a wellhead. The main body houses the annular seal assembly that includes a pressure set seal pack for sealingly engaging the polished rod. The polished rod reciprocatingly extends through the seal assembly and main body. The seal assembly includes paired metal annular cones which are capable of sealing under conditions present in the stuffing box. The seal assembly withstands such conditions far longer than traditional seal assemblies, thus reducing cost and downtime of the pumping unit.

RELATED U.S. PATENT DOCUMENTS

This patent application is an original patent application in the UnitedStates. No federal funding was used in the development of thisinvention.

DESCRIPTION Summary of the Invention

The present invention provides a stuffing box having an improved designof a pressure active seal assembly consisting of pairwise arrangementsof hollow cones, which adds unexpected long life to the seals thereof.

BACKGROUND OF THE INVENTION

Standard oil pumping units, also known as pumpjacks, have severalcomponents that are essential for operation. One such unit is thepolished rod, which is visible from the exterior of the unit. Thepolished rod moves up and down in a vertical plane, when the unit is inoperation.

The polished rod moves through a stuffing box, which contain seals thatlubricate the polished rod, and yet seal the unit to prevent oil leaks.These seals are often constructed of graphite or other soft, malleablematerial, in order to closely conform to the motions of the polishedrod.

The difficulty with graphite seals, or seals of other soft material, isthat they are not durable. Seals must be replaced frequently, at highreplacement cost, due to manpower needs, replacement materials, and downtime of the pumping unit. Yet, prior to the present invention, it wasdifficult to engineer hard materials to produce seals of long life andduration.

A primary object of this invention is the provision of an improvedstuffing box for a unit, or the like, having a seal assembly mountedwithin a main body thereof. There is a seal pack included within theseal assembly which is supported within a seal holder therefor. The sealassembly includes a series of pairwise mounted metal hollow conicalseals, so configured to fit tightly around the polished rod.

Another object of this invention is the provision of slots in the cones,which allow for expansion and contraction of the cones, according toambient temperature and pressure conditions. This allows the cones tomaintain their function of sealing the rod.

Another object of this invention is to provide a sealing mechanism for apolished rod, which mechanism is comprised of hardened steel or otherhard material.

A significant object of the current invention is to provide a sealingmechanism for an oil producing unit that is significantly more durablethan current devices of the same service. Thus, an important objectiveis to provide more time between replacement services for seals in an oilpumping unit.

The above objects are attained in accordance with the present inventionby the provision of a combination of elements which are fabricated in amanner substantially as described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings constitute a part of this specification and includeexemplary embodiments to the invention, which may be embodied in variousforms. It is to be understood that in some instances various aspects ofthe invention may be shown exaggerated or enlarged to facilitate anunderstanding of the invention.

FIG. 1 is a longitudinal side view of the current invention, withpartial translucency of the outer surface in order to indicate thepresence of interior components.

FIG. 2 is a longitudinal side view of the current invention, with thehead cap removed.

FIG. 3 is a longitudinal, cross-sectional, side view of the currentinvention, with interior components displayed.

FIG. 4 is a side view of a single truncated annular hollow cone of thecurrent invention.

FIG. 5 is a cross-sectional, view form below of the base of a singletruncated annular hollow cone of the current invention.

FIG. 6 is a side view illustrating details of a single truncated annularhollow cone of the current invention.

FIG. 7 is a perspective lower side view illustrating details of a singletruncated annular hollow cone of the current invention.

FIG. 8 is a side view of the cap of the housing cylinder of the currentinvention.

FIG. 9 is a side view of the base element of the housing cylinder of thecurrent invention.

FIG. 10 is a view of a pumping unit, or ‘pumpjack’, embodying thecurrent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Detailed descriptions of the preferred embodiment are provided herein.It is to be understood, however, that the present invention may beembodied in various forms. Therefore, specific details disclosed hereinare not to be interpreted as limiting, but rather as a basis for theclaims and as representative basis for teaching one skilled in the artto employ the present invention in virtually any appropriately detailedsystem, structure or manner.

FIG. 1 discloses the overall structure of the novel packless stuffingbox 100 of the current invention. The ‘box’ is actually a cylindricaltube, with sealing elements inside the tube.

The main body of the outer tube 200 has upper and lower end caps, 20 and40, respectively. The entire unit is designed to fit snugly around apolished rod, at the lower end thereof, near the borehole exit.

A schematic depiction of stuffing box 100 is shown in FIG. 2. The hollownature of the tube 200 is emphasized in this depiction.

FIG. 3 reveals more details of the current invention 100. The head 20 isshown at the bottom, with exit ports 25 to vent gases. Interior to themain body are pairs of annular seals 50, in the form of truncated cones.The cones fit pairwise, base-to-base in each pair. Pairs meet otherpairs at top-to-top junctures 70. Optionally, O-rings or other sealantaid may be used at these junctions 70 to ensure a tight seal.

When assembled, the cones and main body form a channel 80 into whichwill fit a polished rod of a pumpjack unit. The rod can move up and downin a vertical plane, or can rotate around its long axis. The presentinvention will maintain a tight seal and prevent the escape of oil.

An annular seal cone 50 of the preferred embodiment of the currentinvention is shown in FIG. 4. The cone is hollow, and open at both itstop and its base. Preferably the cone is constructed of steel. The conealso has a through slot 54, and a recessed base 56. The slot allows forexpansion and contraction as temperatures and pressures increase anddecrease. The recessed base allows for tight coupling with another sealcone, to form the pairs shown in FIG. 3. The hollow area inside the coneis designed to accommodate the shaft of the polished rod in a pumpjackunit.

FIG. 4 portrays one of the paired metal sealing cones 50 in aperspective view from the side. The cone is truncated at the top, andopen at both top and bottom, and is hollow. Preferably the cone isconstructed of ⅛ inch carbon steel. The cone has a through slot 54extending vertically from the top to the bottom of the cone. This allowsfor thermal expansion of the ring without damaging the walls of thecone. Other slots (no shown in FIG. 4) are desirable, but must not bethrough slots, in order to preserve the integrity of cone 50. Alsopresent on the cone 50 is a channel 56 that runs along the lower edge ofthe cone, at the base. This channel allows for close fitting of twopaired cones 50, base to base.

FIGS. 5 and 6 display the sealing cone 50 from alternate view angles.FIG. 5 shows a preferred embodiment of cone 50, viewed from its base.From this vantage point, through slot 54 and partial slots 58 areclearly seen. The slots are optimally placed at 120-degree intervalsaround the circumference of the cone. The dashed line 59 represents thewall of the cone 50 rising behind the base in this view.

Turning now to FIG. 6, sealing cone 50 is displayed upright, from a sideview. Here the bottom channel 56 is clearly displayed, as is throughslot 54, rising vertically from base to top of truncated cone 50.Partial slots 58 are also shown, but in the preferred distribution ofslots, partial slots 58 would be obscured in this view, as they lie onthe rear side of the cone as viewed from the side of through slot 54.

FIG. 7 displays the same cone from the base in a perspective view. Thedepressed base 56 is shown, with through slot 54 and partial slots 56displayed to advantage.

The entire stuffing box 100 has a cap and a base. The cap is shown inFIG. 8. The cap preferably has various levels of fit, providingmicrochannels for oil to flow in and around the cones.

FIG. 9 shows the base of the entire stuffing box. Although not seen inthis side view, the base is also hollowing, in order to accommodate thepolished rod. Thus, there will be a through hole inside the base, fromtop to bottom, of the dimensions of the polished rod.

FIG. 10 shows how the present invention 100 fits into its designedoperational environment. The standard oil pumpjack unit comprises awalking beam, a head, and a polished rod or ‘sucker rod. The polishedrod extends down to the wellhead of the oil well. At the junction of thepolished rod and wellhead, a stuffing box, such as that of the currentinvention, is placed to create a seal preventing oil leaks, and allowingthe unit to pump oil from the ground.

As shown in FIG. 10, the current invention 100 will act as a sleeve, orcollar, around the polished rod as it meets the wellhead. The rod movesup and down, forcing oil to the surface, while the stuffing boxpreserves proper pressure and prevents leaks.

The new combination of the novel packless stuffing box and pressure setseal packs provides new and unobvious and patentable features thatreduce the cost of producing an oil well with a pump jack unit.

While the invention has been described in connection with a preferredembodiment or embodiments, it is not intended to limit the scope of theinvention to the particular form set forth, but on the contrary, it isintended to cover such alternatives, modifications, and equivalents asmay be included within the spirit and scope of the invention as definedby the appended claims.

1. An annular seal assembly and stuffing box for an oil pumping unit;said seal assembly and stuffing box comprising: a housing body having anupper end opposed to a lower end, adaptor means at said lower end bywhich said housing can be mounted respective to said pumping unit; saidhousing body having a closure means at said upper end of said main bodythat forms a cap; a longitudinal passageway extending through saidhousing body through which said polished rod can extend; a seal assemblyhaving a plurality of mated, opposing hollow, annular cones, said conesfacing each other base-to-base within each pair, said cone pairs beingaxially aligned with said polished rod and forming part of said innersurface of said seal assembly for sealingly engaging said polished rod;whereby, said seal assembly can seal off and accommodate movement ofsaid polished rod.
 2. The stuffing box and seal assembly of claim 1wherein said housing comprises a cylindrical tube within which said sealassembly fits.
 3. The stuffing box and seal assembly of claim 1 andfurther including a screw cap forming the upper end of said stuffingbox.
 4. The stuffing box and seal assembly of claim 1 wherein said sealassembly comprises annular cones, wherein each cone has a slot cutentirely through one wall, extending vertically therethrough, from topto base.
 5. The stuffing box and seal assembly of claim 1 wherein eachsaid annular cone further comprises a plurality of slots that extendvertically from top to base, but only extend part of the thickness ofthe wall of the cone from the outer wall toward but not penetrating theinner wall of said cone.
 6. The stuffing box and seal assembly of claim1 wherein each said annular cone further comprises a cut down lower edgeof the cone at the base thereof.
 7. An improved stuffing box and annularseal assembly of the type that can be connected to a tubing, and havinga shaft received therethrough in a sealed manner therewithin and forms atubing annulus therewith, comprising: said box comprising a hollowcylinder, having a longitudinal passageway extending therethroughthrough which said shaft can be received for either of rotational andreciprocating movement; wherein, an axial passageway extendslongitudinally through said seal assembly in parallel relationshiprespective to said longitudinal passageway of said box; a seal packincluding pairwise arrangements of hollow truncated cones mounted withinsaid seal holder for sealingly engaging said shaft.
 8. The stuffing boxand seal assembly of claim 7 wherein said seal pack comprises upper andlower paired annular truncated cone seal elements having a porous oilingchannels located therebetween, and passageway means connecting saidporous oiling channels for lubricating said seal assembly and saidshaft.
 9. The stuffing box and seal assembly of claim 7 wherein saidshaft is reciprocatingly connected to a pumping unit, said seal assemblyis arranged for radial movement within said chamber in a manner suchthat said longitudinal passageway can be moved in any radial directionwithin a plane that lays perpendicular to said shaft to therebyaccommodate misalignment between a pumping unit horsehead and a verticalaxis of a borehole.
 10. An annular seal assembly and stuffing box for anoil pumping unit; said seal assembly and stuffing box comprising: ahousing body having an upper end opposed to a lower end, adaptor meansat said lower end by which said housing can be mounted respective tosaid pumping unit; said housing body having a closure means at saidupper end of said main body that forms a cap; a longitudinal passagewayextending through said housing body through which said polished rod canextend; a seal assembly having a plurality of mated, opposing hollow,annular cones, said cones facing each other base-to-base within eachpair, said cone pairs being axially aligned with said polished rod andforming part of said inner surface of said seal assembly for sealinglyengaging said polished rod; wherein, said cones each have a plurality ofslots cut vertically into the walls thereof; and, whereby, said sealassembly can seal off and accommodate movement of said polished rod.